In next generation multimedia mobile communication systems, which have been actively studied in recent years, there is a demand for a system capable of processing and transmitting a variety of information (e.g., video and radio data) in addition to the early-stage voice service. The wireless communication system is designed for the purpose of providing reliable communication to a plurality of users irrespective of their locations and mobility. However, a wireless channel has an abnormal characteristic such as a fading phenomenon caused by a path loss, noise, and multi-path, an inter-symbol interference (ISI), a Doppler effect caused by mobility of a mobile station, etc. Therefore, various techniques have been developed to overcome the abnormal characteristic of the wireless channel and to increase reliability of wireless communication.
Automatic repeat request (ARQ) is one of techniques for increasing reliability of wireless communication. The ARQ is a technique for retransmitting data by a transmitter when a receiver fails to receive the data. In addition, hybrid automatic repeat request (HARQ) is a technique in which the ARQ is combined with forward error correction (FEC).
In order to increase reliability of wireless communication while supporting a high-speed data service, a wireless communication process is preferably implemented with a plurality of independent hierarchical layers rather than one single-layer. A structure of the plurality of hierarchical layers is called a protocol stack. The protocol stack may refer to an open system interconnection (OSI) model which is a widely known protocol for communication systems.
The ARQ and the HARQ are implemented in different layers. A layer capable of performing the HARQ is called an HARQ entity. A layer capable of performing the ARQ is called an ARQ entity. In general, the ARQ and the HARQ are independently performed. However, performance may deteriorate when the ARQ and the HARQ are independently performed. This is because fast recovery cannot be achieved by the ARQ entity when there is a problem unsolvable by the HARQ entity. As a result, reliability of wireless communication is decreased. Accordingly, there is a need for a method of transmitting a data block by interaction between the ARQ and the HARQ.